This invention relates generally to a synchrotron shutter and more particularly to a synchrotron shutter in which a rotating multifaced mirror is spaced from a slit in appropriate distance and has a timed rotation such that only selected synchrotron pulses reflected off the mirror are directed through the slit.
Subatomic particles such as electrons, positrons, and protons, can be accelerated to high velocities and energies, usually expressed in terms of center-of-mass energy, by machines which impart energy to the particles in small stages or nudges, ultimately achieving in this way very high-energy beams. In a synchrotron, the particles are made to follow a circular or closed curve by arranging a number of magnets in a ring. Groups of particles may circle a ring of this kind several million times while they are increasing their energy and velocity. Ultimately, these accelerated particles are extracted and then directed to strike a fixed target.
Synchrotron radiation is the electromagnetic radiation emitted as a result of continual acceleration toward the axis of rotation of charged particles moving in a magnetic field. It is a source of tunable coherent x-rays, and is used for phase- and element-sensitive microprobing of biological assemblies and material interfaces as well as research on the production of electronic microstructures with features smaller than 1000 angstroms.
Typically, synchrotrons provide millions of intense light pulses per second. In studying changing structures of complex crystals, the experimentalist can, at best, irradiate samples with a minimum of several hundred pulses. In contrast to conventional synchrotron experiments, the key to performing time-domain research is the ability to select a single pulse from the millions provided. The timing of the selection may also be dependent on the timed exposure of the crystal to a laser pulse or other energy to induce structural and/or chemical change. One solution is to use a rotating slit for the selection. However, at the excessive speed of the pulsed beam, the slit rotation would be difficult to achieve with the desired speed and accuracy. No existing synchrotron facility can conduct such single-bunch experiments.
One of the most challenging problems in natural artificial photosynthesis research is the direct detection of structural changes accompanying photophysical and photochemical reactions, especially those with very fast reaction rates. In these cases, conventional steady-state X-ray diffraction, small-angle scattering, and X-ray absorption techniques have very little chance of success. However, synchrotron radiation, a source of intense pulsed X-rays, provides the potential to monitor fast structural changes via time-resolved X-ray spectroscopies and diffraction. The synchrotron source, with an ultimate time resolution of less than 50 ps, has the great potential of detecting structural changes occurring on a comparable time scale.
Accordingly, it is an object of the present invention to control the repetition rate of synchrotron pulses.
Another object of the present invention is to select a single pulse or bunch from a large number of pulses in an x-ray beam on which to direct a crystal.
A further object of the present invention is to provide a mechanism for the study of:
1) time-domain structure determination using EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure);
2) time-resolved crystallography; and,
3) X-ray radiation-damage studies.